Apparatus for casting molten metal/foaming agent composition

ABSTRACT

A novel vessel and an improved method of casting batch liquid materials which solidify on cooling or standing utilizing one or more upright open-ended body elements with mixing means therein initially seated on the bottom of a mold; the method is especially advantageous for casting foamed metals.

United States Patent [191 Jarema et al.

[ APPARATUS FOR CASTING MOLTEN METAL/FOAMING AGENT COMPOSITIONlnventors: Chester P. Jarema, Detroit; Leonard M. Niebylski, Birmingham,both of Mich.

[73] Assignee: Ethyl Corporation, Richmond, Va.

[22] Filed: Apr. 24, 1972 [21] Appl. No.: 247,040

Related US. Application Data [63] Continuation-in-part of Ser. No.50,139, June 26,

1970, abandoned.

[51] Int. Cl B22d 41/00 [58] Field of Search 164/136, 335; 75/20 F,75/222; 264/41; 425/256, 447, 817

[56] References Cited UNITED STATES PATENTS 2,533,986 12/1950 Atterbury..425/447X [11] 3,826,303 [451 July 30, 1974 4/1961 Willemsen 425/4122/1967 Bjorksten 164/79 X FOREIGN PATENTS O R APPLICATIONS 8,284 4/1913Great Britain .[164/136 322,169 6/1920 Germany 164/136 PrimaryExaminerRobert D. Baldwin Attorney, Agent, or FirrriDona1d L. Johnson;Robert A. Linn ABSTRACT 2 Claims, 9 Drawing Figures t u ji m I 3 I S r s4 g- 2/ Pmmmma 3.826.303

SHEET 10? 3 FlGURE 2 FIGURE 3 Fl U RE 4 INVENTOR.

CHESTER P. JAR-EMA LEONARD M.N|EBYLSKI PAIENTEUJUUOIHH SHEEI 3 OF 3-FIGURE IA APPARATUS FOR CASTING MOLTEN METAL/FOAMING AGENT COMPOSITIONCROSS REFERENCE TO RELATED APPLICATION This application is aContinuation-in-Part of copending application Ser.' No. 50,139, filedJune 26, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention is directed to an improvedapparatus for batch casting liquid materials especially foamed metals,utilizing a novel vessel.

Casting, that is, transferring a liquid material to a mold where it willsubsequently solidify is ordinarily accomplished by pouring the liquidmaterial out of the vessel containing the liquid material directly intoa mold. Simple examples are pouring a gelatin dessert into a mold,pouring water into an icecube tray for freezing, and the like. Wheretransfer time is an important element in casting, e.g. polyurethanefoams, liquid elastomers, liquid resins, e.g. epoxy resins and polyesterresin, metal foams and the like, pouring the liquid material from itscontainer into a mold can create problems such as poor mold filling,undesirable air entrapment, loss of material due to set up in thecontainer and the like. The problem with casting foamed metals, such asfoamed aluminum, is particularly perplexing because of the relativelyshort time interval between adding a foaming agent to the molten metaland foam formation. One expedient which has been utilized successfullyin overcoming some of the aforesaid problems is the use of a continuousmethod of preparing and casting the liquid material. This continuouspreparing/casting system has been applied to foamed metal casting asillustrated in the following U. S. Pat. Nos.: 2,937,938, 2,974,034,2,983,597, 3,005,700, and 3,214,265.1-Iowever, this expedient is notapplicable to batch operat1ons..

It has been discovered that in batch operations, a very rapid transferof castable liquid material from the holding and/or preparing containerinto the mold can be achieved by using a novel vessel in which the moldbottom serves as the bottom of the mixing vessel. Thus, especially whentransfer time is important for example, with foamed metals, the transferof liquid to the mold can be directly and efficiently accomplished withessentially no time lag by simply separating the mixing vessel from themold when the liquid material is ready to be cast. In this way, theliquid material quietly, smoothly and rapidly flows directly into themold, avoiding problems associated with pouring.

SUMMARY OF THE INVENTION An improved'vessel for casting and/or preparingcasting liquid materials comprises (a) one or more main body elementsopen at opposite ends which provide cavity for holding said liquid, and(b) a bottom element which seals the lower aforementioned open end andis also the bottom of a mold into which the material is to be cast. Afeature of the vessel is that the bottom element and main body elementsare completely vertically separable An improved'method of casting liquidmaterials especially foamed metals utilizes said vessel.'

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 isa section view through avessel of the present invention. FIG. 1A is a section view through thevessel of the present invention showing a stirring means 8.

FIG. 2 is a section through the vessel of FIG. 1. It shows the bodyelement 1 separated from the bottom element 4 permitting the liquidmaterial 2 to flow into the bottom element 4.

FIG. 3 is a section through a vessel of the. present invention havingtwo body elements, 1 and 1.

FIG. 4 is 'a section through the vessel of the present invention. Itillustrates a hemispherical body element la.

FIG. 5 is a side view section of a substantially hemispherical main bodyelement having a lower opening lb of different shape.

FIG. 5A is a top view section of FIG. 5 at A-A', showing the shape ofthe lower opening 1b.

FIG. 5B is a partial section top view of FIG. 5 section at'BB and thebottom element 4. It shows the pattern of the liquid material2 flowingout of the main body element 1 into the bottom element 4.

FIG. 6 is a partial section view of a vessel of the present invention.It includes an illustration of a sectioned heating element 7 whichsurrounds the main body element 1. A platform 5 driven by a piston 6holds the bottom element 4 in a sealing position against the main bodyelement 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of this inventionis a novel vessel for casting and/or preparing a castable liquidmaterial. The vessel comprises (1) at least one main body element openat opposite ends in which the liquid material to be cast is held and (2)a bottom element which seals the lower of said open ends. The bottomelement is also the bottom of a mold into which the liquid material isto be cast. When the liquid material is ready to be cast, the bottomelement and main body elements are vertically separated. The liquidmaterial thus immediately and directly flows into the mold(which is thebottom element). As compared to any standard techniqueof'casting whichrequires a pouring operation, the present method utilizing the novelvessel substantially reduces the time lag between ready to cast" andcast; and since there is no actual pouring from one container intoanother, splashing and problems caused thereby are also virtuallyeliminated.

The method of casting liquid materials utilizing the vessel of thepresent invention is also an embodiment of this invention.

Referring to the drawings, FIG. 1' illustrates in cross section a vesselof the present invention. The main body element 1 is open at both ends.It provides a cavity in which the liquid material 2 to be cast is held.The lower end of the main body element 1 is provided with a suitablegasket 3 against which the bottom element 4 is seated, thus sealing themain body element 1 and holding the liquid material 2 therein. FIG. 1Ashows a stirring means 8 within body element 1. FIG. 2 shows the vesselof FIG. 1 shortly after the two elements 1 and 4 are separated and theliquid material 2 flows directly into the mold or bottom element 4. FIG.3 illustrates a vessel in which two main body elements 1 and l areutilized. The number of main body elements may be varied as theparticular total system requires. FIG. 4 illustrates a vessel of thepresent invention in which the main body element 1 is hemispherical inshape. FIG. 5 shows a hemispherical main body element 1a with a loweropening 1b of different shape than the main body element 1. FIG. 5Ashows that said opening lb is substantially rectangular. FIG. 5B shows atop view of FIG. 5 at section B-B' in which the bottom element 4 or moldhas the same shape (rectangular) as the lower opening of main bodyelement 1. The desirability of the main body element 1, or at least thelower opening of said body element, and the bottom element or moldhaving substantially the same shape improves the liquid flow pattern bymaking it better coincide with the mold shape. FIG. 6 shows an assemblywhich includes a heating element in section 7 which surrounds the mainbody element 1 and a platform 5 driven by a movable piston 6 whichserves as the means for holding the bottom ele ment 4 in a sealingposition against the main body element 1; and which also permitslowering of the bottom element 4 from the main body element 1 when theliquid material held in the main body element It is ready to be cast. i

Although the method and apparatus of the present invention can be usedwith any castable material which is ordinarily liquid or can beliquitied as for example by heating, the present method is of especialvalue when batch casting liquid materials in which time from readyto-cast to cast is of importance. Our method is especially of value withbatch casting a liquid mate rial which subsequently foams in the mold,especially when the liquid material is molten metal. By batch casting ismeant preparation of a certain volume of liquid material which is thenused to fill a discrete mold or molds. This is in contrast to continuouscasting where the liquid materials are being mixed and fed continuouslyeither to a discrete mold or to a moving mold for example,a shapedconveyor belt.

The present vessel may be constructed of any materials which aresuitable for handling the particular liquid material which is to becast. In other words, if the liquid material were corrosive, then amaterial of construction which wouldnot be attacked by the liquidmaterial should beused; and if a considerable amount of heat is requiredto liquify and prepare the material (e.g., metal) for casting, thematerialof construction should be sufficiently heat resistant. Thus, theproperties and characteristics of the liquid. material to be cast willhelp determine the type of construction material required for thepresent vessel.

Although the bottom element may seat directly against the lower open end'of the main body elements, a gasket is more conveniently provided atthe lower end to facilitate sealing. This is illustrated in FIGS. 1-4and 6. This gasket material should be a material which will withstandthe conditions which are required for casting and/or preparing liquidmaterials. The gasket should bottom element or, mold'which comprises thepresent vessel can-also be varied as required. Ordinarily, where themain body element of the present vessel is also utilized to prepare theliquid casting material and agitation and mixing of the ingredients isrequired, then main body element shape which would facilitate suchmixing would best be used. With regard to the volumes of the main bodyelements and the mold or bottom element of the present vessel, there isno fixed relationship although ordinarily the volume provided by themain body elements should be adequate to hold sufficient liquid materialto fill the mold or bottom element to the desired level. The size of thelower open end of the main body elements should also be adequate topermit the flow of liquid material into the mold to be accomplished inthe time required for the system.

Although the shape of the main body element and the bottom element ormold of the present vessel are not directly interrelated, it ispreferred that at least the lower open end of the main body element andthe mold or bottom element be of similar shape (see FIG. SB forexample). By maintaining such a shape relationship, the flow patternofthe liquid material during the casting step is such as to effect a moreuniform'flow of liquid from the main body element into the mold orbottom element. Thus, for example, if a square mold served as the bottomelement of a vessel of the present invention and the material to be castrequired maximum mixing and agitationthen a hemispherical main bodyelement having a square opening at its lower end (see FIG. 5A forexample) would provide a most efficient flow pattern for casting theliquid material. If desired of course, the shape of the entire bodyelement may be uniform with said open end. It is also contemof any moldby the use of a detachable lower end openlowing aluminum alloys areexamples of useful alloys for preparing suchfoam: ALUMINUM ASSOCIATIONDESIGNATION A 7075 (l.6lo Cu, 2.5/o Mg, 0.3/o Cr, 5.6/o Zn, re-

mainder A1) 2024 (4.5/0 Cu,-

A1) 5086 (0.45/o Mn, 4 .0/o Mg, 0.l/o Cr, remainde A1) 6063 (0.4/o Si,0.7/o Mg, remainder Al) Almag 35 (6 8/0 Mg in Al) 1,000 series A1(9-9.6/o minimum Al) 201 l (5.5/o Cu, 0.S/o Pb, 0.5/o Bi (remainder Al)7 /0 Mg, remainder 2218 (4.0/o Cu, 1.5/o mg, 2/o ni, remainder A1) 3005(l.2/o Mg, 0.4/o Mg, remainder A1) 4042 (12.2/o Si, 0.9/o Cu, l.1/o Mg,0.9/o Ni,

- remainder Al) 4043 (5lo Si, lo A1) 8280 (l.5/o Si, 1.0/o Cu, 0.5/o Ni,remainder Al) Magnalium 70/o Al, 30/o Mg In general, preparation offoamed metals involve blowing the molten metal with a suitable gasgenerating (cellulating or foaming) agent such as magnesium hydride,titanium hydride, zirconium hydride and the like. Air properly entrainedin a molten metal may also be used in preparing metal foam. Where ablowing agent such as a metal hydride, preferably zirconium hydride, isused, a viscosity controlling additive may be added to the molten metalduring the preparation of the foam to help control the foam density andpore uniformity. The viscosity controlling agent is generally addedbefore the foaming agent (or air) is introduced into the molten metal.Representative examples of foam compositions and methods of preparingthe molten mixtures are found in the patents cited above.

To illustrate the advantages of the present vessel and method in castingfoamed aluminum, a batch of molten aluminum alloy containing zirconiumhydride blowing agent and CO as a viscosity control additive wasprepared in a heated mix pot with adequate agitation. The mix pot wasprovided with a bottom which could be opened to permit the moltenaluminum mixture to pour into a mold placed beneath the pot. When themolten aluminum mixture was ready for casting the bottom of the pot wasopened, and the molten aluminum mixture poured into a mold held beneaththe mix pot. The cast aluminum mixture in the mold was then cooledexternally by means of air blowers. The resultant molded aluminum foamwas examined and found to have imperfections caused by splashing andsplattering in the center of the mold where the molten metal poured fromthe mixing pot. This splashing and splattering also caused envelopmentof air which resulted in further defects in the foam.

Substantially the same composition of molten aluminum alloy containingzirconium hydride and CO was then prepared in a vessel of the presentinvention. The mixture was prepared in substantially the same way usingthe same agitation system and mixing cycle. The foam was then cast intoa mold, as per the present method, by lowering the mold (or bottomelement) from the main body element until all the molten aluminummixture had flowed into the mold. Transfer of the molten metal from themain body element was quiet, rapid and essentially complete (compared tothe mixed pot method) before the foaming occurred. Thus, the foam wasgenerated in the mold and substantially filled the mold. The castaluminum foam was then cooled by means of air blowers. Examination ofthe cast aluminum foam showed it to be substantially free from any ofthe splashing and splattering defects and consequent air envelopmentdefects using the aforesaid mixing pot. Furthermore, the foam preparedusing the present method was more uniform throughout than the foamproduced using the aforesaid mixing pot method.

It is readily apparent then that the present vessel and method ofcasting liquids and especially molten metals and foams such as aluminumfoams, provides a means for substantially improving batch casting inliquids. In addition to the readily evident substantial improvement inquality of the final cast product, the present vessel and method offerthe following additional advantages compared with conventional mixpot/pour systems:

1 The system is simple in operation.

2 The vessel has no moving parts and consequently dimensional tolerancesare not critical.

3 Transfer of liquid material from main body element to bottom elementor mold is rapid, direct and quiet flow is insured.

4 Loss of casting liquid caused by residual liquid being retained in themain body cavity after casting is substantially reduced; and in the caseof foamed metals such as aluminum, this also effects more accuratecontrol of the foam density.

The present invention has been disclosed above- It encompasses twoembodiments: (l) a novel vessel, and

b is open at opposite upper and lower ends,

2 means, located within said main body elements, for

mixing said molten tion, and 3 a relatively large container-shapedbottom element (a) which is seated against and closes the lower openends of said main body elements during said mixing and (b) which is alsothe bottom of a mold into which said composition is to be cast, saidmain body elements and said bottom element supported by means wherebysaid bottom element is completely and independently vertically separablefrom said main body elements for quiet, rapidand essentially completetransfer of said composition to said mold.

2. The vessel of claim 1 wherein said lower open ends are provided withsuitable gasket means against which said bottom element is seated.

metal/foaming agent composi- $223? UNITED STATES PATENT O E- QERTIFICATEOF CORRECTION Patent No. 3, 826,305 v Dated July 30, 197

Inventor) Chester ,P, Jarema et a1 It is eertified'that error-appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

Page 1, under the heading "ABSTRACT, last line, after .1

"metals add the phrase wherein the mold is independently lowered fromthe body elements for quiet, rapid and essentially complete transfer ofthe molten metal/foaming agent composition to the mold Column 4, line61, aluminum alloy example 2218, "2 ni" should be 2"/ Ni Signed andsealed this 5th day of November 1974.

(SEAL) Attest:

MeCOY M. GIBSON JR. C. MARSHnLL DANN Attestimg Officer Commissioner ofPatents

1. An improved vessel for preparing and casting molten metal/foamingagent composition which consists essentially of 1 one or morecylindrical upright main body elements, each of which a defines a cavityfor holding said composition, and b is open at opposite upper and lowerends, 2 means, located within said main body elements, for mixing saidmolten metal/foaming agent composition, and 3 a relatively largecontainer-shaped bottom element (a) which is seated against and closesthe lower open ends of said main body elements during said mixing and(b) which is also the bottom of a mold into which said composition is tobe cast, said main body elements and said bottom element supported bymeans whereby said bottom element is completely and independentlyvertically separable from said main body elements for quiet, rapid andessentially complete transfer of said composition to said mold.
 2. Thevessel of claim 1 wherein said lower open ends are provided withsuitable gasket means against which said bottom element is seated.